Treating Cold Damaged Plants
As I am writing this, it is 30 degrees and dropping outside in Clay County, Florida and it looks like we have at least two more nights with hard freezes. This is nothing compared to most of the country, but for our landscape and garden plants, this cold can cause some severe damage. I know personally that many of my perennials and hibiscus in my yard, which were still blooming away today, are going to see a hit. If your tender plants are not protected from the frost, here are some tips to weather them through the damage.
Watering before a freeze can help moderate soil temperatures, protecting the roots, so a good rain the day before a hard freeze can be a blessing. Make sure the soil around damaged plants stays somewhat moist and does not dry out completely. If temperatures ever stay below freezing for a prolonged period, watering may help defrost the soil and give plants some available water. (On a side note, never leave hoses pressurized with water during cold weather, it makes them likely to split or burst).
Do not fertilize
Injured plants make people want to baby them, don’t. Do not fertilize until spring, when the plants begin actively growing again. Fertilization with nitrogen in the winter can lead to even more damage as the young growth nitrogen promotes is very cold sensitive.
Do not prune it back
While it may be ugly, the wilted, brown, and dead plant material associated with frost or freeze damage protects the rest of the plant that is still living. Leave it there until the danger of cold is gone in the spring, then check for fresh growth. Woody plants can be checked by scratching the surface with a fingernail and seeing the color of the wood underneath: black or dark brown wood can be a sign of cold damage. Tender, fleshy plants like begonias or impatiens can be pruned back after cold so they don’t rot and lead to disease.
A browning lawn is normal
With cold weather, many lawns will turn brown as they head into full dormancy, don’t worry, this is normal. If temperatures drop too low, it can cause some permanent damage which can be observed by wilting, turning to a brown or white color, and then a rotting smell. If growth does not resume in the spring, you will likely need to replace damaged areas. A good resource for this issue can be found here.
If you have any specific questions about your cold damaged plants, contact your local University of Florida/IFAS Extension Office for help.